Diagnostic devices incorporating fluidics and methods of manufacture

ABSTRACT

The present invention relates to diagnostic devices incorporating electrode modules and fluidics for performing chemical analyses. The invented devices consist of a sensor array formed on an electrode module, the sensor array being contained within a fluidic housing. The electrode module is a laminate of a perforated epoxy foil and a photo-formed metal foil with sensor membranes deposited into the perforations. The fluidic housing is an element consisting of a plastic card-like body with fluidic conduits and a sealed fluid reservoir contained in a foil-lined cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation in part of patent application Ser. No. 10/307,481 filed Dec. 2, 2002 and entitled Heterogeneous Membrane Electrodes.

FIELD OF THE INVENTION

[0002] This invention relates to unit-use diagnostic test cards comprising sensors and fluidics

BACKGROUND OF THE INVENTION

[0003] Plastic cards in the general shape and size of credit cards, but with embedded integrated circuit chips are well known in the art. Such devices have appeared as articles of commerce in numerous applications where low cost electronic devices for personal use are required, such as bank cards, phone cards and the like. They are known as smart cards or IC cards. There was no teaching in the prior art concerning the use of card systems of this type that have been modified by removal of the integrated circuit chip and addition of fluidic and sensor elements for use in chemical analysis or in-vitro diagnostics, prior to the following published disclosures which are related to this invention.: Electrode Module U.S. patent Publ. No. US 2002/017944 A1, Point-of-Care In-Vitro Blood Analysis System U.S. patent Publ. No. US 2003/0148530 A1.

[0004] In the co-pending and related patent application entitled Heterogeneous Membrane Electrodes, U.S. patent application Ser. No. 10/307,481 there is disclosed a diagnostic card containing a sensor array on an electrode module comprising a heterogeneous membrane reference electrode and electrochemical indicator electrodes, the disclosed electrode module being contained in a credit card sized fluidic housing. This present patent application now discloses additional inventive components and inventive elements of an electrode module and a diagnostic card incorporating fluidic elements.

[0005] Diagnostic test cards and cartridges for chemical analysis are well known in the art. Diagnostic cards and cartridges incorporating sensors and fluidic elements are known in the art. Early examples are U.S. Pat. No. 4,301,412 that discloses a pair of electrodes in a plastic housing with an orifice for sample introduction and a capillary conduit for sample flow to the electrodes. Similar devices were also disclosed in the capillary flow technology described in U.S. Pat. No. 5,141,868. Diagnostic card devices with sensors and fluidics also incorporating on-board fluids contained in sealed housings within the cartridge were disclosed in U.S. Pat. Nos. 4,436,610 and 4,654,127. The '127 device consisted of a plastic card-like housing with sensors and conduits with a sealed chamber containing a calibrating fluid mounted on the card. In use of this device the seal of the fluid-containing chamber was ruptured when the user manually turned a chamber element and subsequent fluid propulsion to the sensors on the card was by gravity. An improved diagnostic cartridge with sensors, fluid conduits and on-board fluid was disclosed in U.S. Pat. No. 5,096,669. This device consisted of a sensor array on a microfabricated silicon chip in a plastic housing with fluidic conduits, as well as a sealed pouch containing a calibrating fluid. The improvement was that the device was designed so that the fluid containing pouch could be ruptured and calibrating fluid moved to the sensors by the read-out instrument rather than manually. In the use of this device the sample is collected into the card away from the sensors, then subsequently moved to the sensor location by an instrument means. In both the '127 and '669 patents the fluid seal is made by a foil coated element and its rupture is by a piercing element that rips through the foil. U.S. Pat. No. 5,325,853 discloses a diagnostic device with sensors and fluidics with on-board fluid that is not sealed remotely from the sensors.

[0006] Of the devices of the prior art only the '669 device has proven commercially useful for the measurement of a broad range of analytes in parallel in sensor panels. The '669 device incorporates many unique and proprietary designs and special purpose components. The manufacturing processes also are unique to their devices and specialized assembly equipment is required. The '669 device and other prior art diagnostic devices generally require numerous process steps in electrode manufacture and numerous piece-parts and precision assembly steps in the card manufacture. Thus, this technology has proven expensive to manufacture, thereby limiting the broader utilization of the technology.

[0007] There are also performance limitations of the '669 technology. The fluid in the foil-lined and sealed reservoir has very limited shelf stability because the seal lengths are short. Furthermore, the reservoir is pressurized during fabrication and the sealed reservoir is ruptured during use by piercing the foil reservoir under applied pressure. Therefore the fluid in the reservoir is under pressure and, thus, has the potential to be evacuated from the reservoir in an explosive manner causing a potential for segmented fluid flow. Such problems can reduce the reliability of the '669 device. The sample transfer into the sample collection area of the '669 device is not done anaerobically. This may result in errors when measuring dissolved gases such as oxygen and carbon dioxide, particularly in samples which have low buffer capacity for those gases. Furthermore, there is no provision for reliable thermostating of the test fluid adjacent to the sensors.

[0008] There is now a need to provide for simpler and more generic designs and manufacturing procedures for sensor arrays and fluidics in diagnostic-card devices.

SUMMARY OF THE INVENTION

[0009] The current patent teaches designs and manufacturing processes to realize fluidic elements in diagnostic cards consisting of low cost components and manufacturing processes. This approach leads to significantly simpler devices than those of the prior art. There are fewer assembled parts, processes are generic and use generic equipment performing low tolerance assembly processes. The result is that devices according to this invention can be manufactured cost-effectively. Furthermore the diagnostic card of this patent incorporates many new inventive features which address performance limitations of prior art devices.

[0010] The invention provides a diagnostic card for use with a card reader in sensing at least one component concentration of a fluid sample. The diagnostic card includes a card body, at least one component sensor located in a sensor region in the card body, a sealed chamber defined in the card body for containing a fluid, preferably remote from the sensor region, a fluid conduit for fluidically connecting the chamber with the sensor region, a valve for fluidically connecting the chamber to the fluid conduit, and a delivery structure separate and distinct from the valve for forcing fluid from the chamber and into the fluid conduit, when the chamber contains fluid and is fluidically connected to the fluid conduit. In a preferred embodiment, the chamber is a hermetically sealed fluid reservoir, preferably in the form of an aluminum foil-lined cavity. The chamber is preferably filled without pressurization so that the contents of the sealed chamber are not under pressure when the chamber is connected to the fluid conduit by the valve. Furthermore, the valve preferably fluidically connects the chamber to the fluid conduit without simultaneous pressurization of the fluid in the chamber. The valve preferably includes a valve body for rupturing a chamber wall from within the chamber. The valve preferably includes a valve body displaceably received in a valve seat in the card body, the valve body being within the chamber, the valve body and valve seat being shaped and constructed for pinching and rupturing a wall of the chamber upon displacement of the valve body relative to the valve seat. The valve body is preferably a rupture plug and the valve seat is preferably a plug receiving bore in the card body, with the plug and plug receiving bore having cooperating edges for rupturing the chamber wall upon displacement of the plug in the plug receiving bore.

[0011] The invention further provides a sensor array on an electrode module incorporated into a credit-card sized plastic card body. The electrode module preferably includes a thin slab that is a laminate of an epoxy foil with a gold coated copper foil. The upper surface of the module is the epoxy foil which is perforated with holes. The lower surface of the module includes the gold coated copper foil which has been formed into an array of at least two electrodes. Each electrode of the array includes a formed element in the shape of a strip which constitutes an elongated electrical path connecting a contact end or contact pad at one end for connection to an external electrical circuit in a card reader, and a sensor end or sensor region under a hole through the epoxy at its other end. The module preferably comprises an array of such strip electrodes, each having a conductor path, a contact end and a sensor end, each sensor end of the array being located at a different hole in the epoxy foil. A sensor is formed on an electrode of the array when a sensor membrane or membranes are deposited into a hole in the epoxy on the top surface of the module, thus contacting the sensor region of the metal electrode on the bottom surface. In a preferred embodiment, a sensor array is made by depositing a different sensing membrane into each hole of each electrode sensing region of the electrode array.

[0012] The module is sealed to the plastic card body so that its upper epoxy surface including the sensor membranes face a fluidic conduit within the card body and the lower metalized surface faces outward and is exposed for external access to the contact pads. The array of holes with sensor membranes, referred to herein as the sensor region, is preferably a substantially linear region exteding along the center of the module, which region aligns to a substantially linear fluidic conduit in the plastic card body so that fluid flowing through the fluidic conduit during use of the device contacts the sensor membranes of the array in the sensor region. The portion of the module's epoxy surface not located in the sensor region is sealed off by adhesive between the plastic card body and the module so that fluids are retained within the conduit at the sensor region and do not escape to or around the edge of the module.

[0013] In a preferred embodiment, the metal layer of the electrode module further includes a metal heater element in a heating region on its lower surface that is electrically isolated from the sensor electrodes and intended for contact with a first heater block contained in a card reader. The module's metal heater element is a formed element in the shape of a split ring which substantially surrounds the sensor region of the sensor array. The ring is split at one, two or more locations, that is to say the metal heater element preferably comprises of two or more shaped metal elements which together form the split ring surrounding the sensor region of the module. Each split represents a connecting gap connecting the sensing and contacting regions of the module. Each electrode of the electrode array now has the conductor path which connects the sensor end of the electrode to the contact end passing through a connecting gap so that the electrodes of the array are electrically isolated from the metal of the heater element. The conductor paths of the electrode array are preferably formed so that they are especially long and thin so that heat transport from the sensor region to the contact region is minimized. In one embodiment, a separate connecting gap is provided for each conductor path. In another preferred embodiment, the contact ends and connecting gaps are distributed about the sensing region so that all conductor paths are of equal length.

[0014] During use, a diagnostic card in accordance with the invention is inserted into the card orifice of a read-out instrument. The card's electrode module makes electrical contact at each of the contact pads of the electrode array to a z-action connector contained within the card reader. The card's electrode module also makes contact at its metal heater region to a first heater block also contained within the card reader. The first heater block is coplanar with the card's module surface and proximal to it when the card is in the card-reader's card insertion orifice. The first heater block makes physical contact to the metal heater region of the module, but also extends to cover the entire sensor region and a substantial region of the electrical paths, in close proximity but not in physical contact. This allows efficient heat transfer to the paths, but maintains electrical isolation from them. Thus, the first heater block heats the sensing region of the module and the fluid in the card's fluidic conduit above the sensing region by direct thermal conduction from the block to the module's metal heater region, as well as indirectly through an air gap at the sensor region and thence to the sensors and fluids, and indirectly through a thin air gap to the electrical paths of the electrode array. This configuration accomplishes thermal bootstrapping of the electrode paths, which further minimizes the heat transport from the sensor region to ambient along the paths. This configuration thus provides for more uniform temperature control of the sensor region. A second heater block of the card reader is coplanar with the card's upper surface and proximal to it when the card is in the card-reader's card insertion orifice. The second heater block makes physical contact to the card's upper plastic surface. The second heater block covers the sensor area of the card but extends a distance along the direction of the fluidic channel in both directions away from the sensor area. This provides heat to the fluid in the fluidic conduit in the regions immediately upstream of the sensor area and immediately downstream. This minimizes heat flow from the sensor region along the fluidic conduit by effectively thermally bootstrapping the fluid in the conduit. Thus the card's entire sensor area, the fluidic conduit proximal to the sensor area, the sensors'electrical paths and the fluid in the conduit upstream and downstream of the sensor area are all contained within a thermostatted cavity comprising heater blocks above and below. This arrangement allows rapid heating of a cold sample fluid to its control temperature, and also accomplishes very precise thermostatting to the control temperature.

[0015] In another aspect of the diagnostic card of this invention there is provided a connector means in the read-out device for connection to the card's electrode module. The connector means is a z-action connector comprising an array of contact elements, being formed metal films on a flex substrate, which flex-substrate is placed on a flexible cantilever, preferably a plastic cantilever. The cantilever is positioned so that when the card is inserted into the card reader's card insertion orifice the module's outer surface with its contact pad array is proximal to the contact elements of the flex substrate and the cantilever is depressed so as to apply z-action force between the connector array on the flex substrate and the contact pad array on the module. Because the electrical contacting elements are thin metal films on a flex substrate, the invented flex connector drains far less heat than conventional z-action connector pins used to contact smart cards of the known art. Additionally, the flex substrate and its connector array can also incorporate electronic components of card reader's electrical circuitry, resulting in a cost reduction of the card reader.

[0016] In still another aspect of the diagnostic card of the invention there is provided an improved design for the sealed calibrator reservoir. In the previously disclosed card of co-pending U.S. patent application Ser. No. 10/307,481 the calibrator reservoir comprised a cavity in the card's plastic body, which after filling with calibrator fluid was sealed by an overlayer of a metal coated foil element. We have found improved lifetime of the sealed calibrator when the cavity in the plastic card body is clad on both sides with an aluminum foil lamination. The new design comprises a diagnostic card with a sensor array on an electrode module, and a sealed calibrator fluid reservoir, which when the seal is ruptured during the use of the device, becomes fluidically connected to the module's sensor region. The reservoir comprises a cavity in the card body, a first plastic-film-coated aluminum foil deformed into the cavity so that the foil contacts the plastic surface of the cavity with its aluminum surface facing the plastic of the cavity and the foil extends beyond the perimeter of the cavity, a calibrator fluid in the cavity, and a second plastic-coated aluminum foil element overlaying the first with its plastic surface facing the plastic surface of the first foil element, and a fused plastic-to-plastic seal between the two foil elements which hermetically seals the calibrator fluid, the seal being formed in the region around the perimeter of the cavity. For good room temperature stability of the calibrator fluid in the sealed reservoir, we have preferred that the width of the perimeter seal be at least 3 mm along the entire perimeter, thus providing a long leakage path for material to escape through the fused plastic seam joining the first and second metallized cladding layers.

[0017] In another aspect of the improved calibrator fluid reservoir, there is provided an improved rupture means for automatically rupturing the foil seal upon use of the device, so as to enable the subsequent delivery of calibrator fluid to the measurement cell which is the fluidic cavity above the sensor region of the card's electrode module. In this improved rupture means there is a plug sealed between the metal foil cladding elements of the calibrator chamber. This plug is caused to move when the card is inserted into the card reader's card insertion orifice which movement causes rupture of the metal foil cladding. A conduit fluidically connects the calibrator reservoir at its point of rupture to the measurement cell, enabling displacement of calibrator fluid to the measurement cell after rupture of the seal.

[0018] In another aspect of the diagnostic card of the invention there is provided an improved design for the sample entry port. An adhesive gasket around the sample entry hole in the card's housing permits a reliable fluid- tight seal between a syringe containing sample fluid and the card. A reliable seal results with little skill required by the operator to engage the syringe to the card.

[0019] All inventive aspects of the diagnostic card of the invention are preferably accomplished in a substantially flat credit-card sized form. Being flat enables efficient stacking of the cards during their storage, as well as enabling a simple engagement to two coplanar clamping elements in the card reader's card insertion orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Preferred embodiments of the invention will now be described in more detail by way of example only and with reference to the attached drawings, wherein

[0021]FIG. 1A is a side view schematic of one preferred embodiment of an electrode module and sensor membranes in accordance with the invention;

[0022]FIG. 1B is a bottom view schematic of another preferred embodiment of an electrode module in accordance with the invention and showing the positioning of the metal foil elements;

[0023]FIG. 1C is a top view schematic of an electrode module showing the sensor region, the heater region and the contact region of the embodiment of FIG. 1B;

[0024]FIG. 2A is a top view schematic of one preferred embodiment of a diagnostic card in accordance with the invention including an electrode module and a sealed calibrator fluid chamber with fluidic connections;

[0025]FIG. 2B is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path BA′ shown in FIG. 2A;

[0026]FIG. 2C is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the card insertion orifice of the card reader;

[0027]FIG. 2D is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the partially clamped card insertion orifice of the card reader;

[0028]FIG. 2E is a side view schematic of the embodiment of FIG. 2A shown in cross-section taken along the fluidic path AA′ shown in FIG. 2A, and the fully clamped card insertion orifice of the card reader;

[0029]FIG. 3A is a side view schematic of the electrode module embodiment of FIG. 2A embedded in the body of the card of FIG. 2A shown in cross-section taken along line M′ of the electrode module of FIG. 1C, and the position of the card reader's heater blocks;

[0030]FIG. 3B is a side view schematic of the electrode module embodiment of FIG. 2A embedded in the body of the card of FIG. 2A shown in cross-section taken along BB′ of the electrode module of FIG. 1C, and the position of the card reader's heater blocks;

[0031]FIG. 4A is a top view schematic of the calibrator fluid chamber and valve of the card embodiment of FIG. 2A;

[0032]FIG. 4B is a side view schematic of the calibrator fluid chamber (before fluid fill) of the card embodiment of FIG. 2A shown in cross-section taken along AA′ shown in FIG. 4A;

[0033]FIG. 4C is a side view schematic of the calibrator fluid chamber (after fluid fill and seal) of the card embodiment of FIG. 2A shown in cross-section taken along M′ shown in FIG. 4A; and

[0034]FIG. 4D is a side view schematic of the calibrator fluid chamber (after fluid fill and seal) of the card embodiment of FIG. 2A shown in cross-section taken along BB′ shown in FIG. 4A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] We describe herein in more detail a preferred embodiment of a diagnostic card in accordance with the invention, formatted for use with a sensor array on an electrode module.

[0036]FIG. 1A shows a cross-sectional view of an electrode module, fabricated using standard smart-card chip-module technology known in the art. The electrode module is described in detail in U.S. patent Publ. No. US 2002/017944 A1, which is incorporated herein by reference. We now disclose new inventive features of the module and its use as part of the diagnostic card and card reader.

[0037] The module 101 of FIG. 1A comprises an epoxy foil element 102 laminated to a gold coated copper metal foil 103 with optional adhesive 102A. The epoxy foil element 102 has through-going holes at 104A and 104B. The metal foil 103 is formed into an array of electrode elements 130. The construction of the electrode elements will be discussed in the following by way of a pair of electrode elements 130A and 130B. Each electrode element 130A and 130B has a connection end 131A, 131B for connection to a measuring circuit in a card reader (not shown) and a sensor end 132A and 132B under the through-going holes in the epoxy 104A and 104B. The electrode module is received from the vendor on a 35 mm web. During manufacture, membranes 105A and 105B are applied to the module on the web extending laterally beyond the perimeter of the holes 104A, 104B and overlaying the top epoxy surface, and extending through the holes to contact the metal electrodes at the sensor ends 132A and 132B. After printing of the membranes, the module is excised from the web using a die cutter, then placed and sealed into a housing in the diagnostic card as described later. In the preferred embodiment, the excised module of the FIG. 1 design is about 11 mm square by 120 micrometers thickness.

[0038]FIG. 1B shows a bottom view (metal foil side) of a module with eight electrode elements, comprising the laminated epoxy foil 102 and metal foil 103. This figure shows in more detail the spatial arrangement of the metal electrode elements. As in FIG. 1A, two electrodes 130A, 130B, representative of the eight, are labeled to show the relationship between their sensor ends 132A and 132B and their connection ends 131A and 131B. There is a metal conductor path 133A, 133B between each electrode's sensor end 132 and its connection end 131, the path 133A extending between connector end 131A and sensor end 132A and the conductor path 133B extending between the connector end 131B and sensor end 132B. The metal conductor paths 133 are generally long and thin to minimize lateral heat transport along them when the module is being heated. Heater contacts 134A, 134B of the metal foil 103 are electrically isolated from the eight electrode elements. These regions are for physical contacting by a heater block of the card reader, as described in more detail later.

[0039]FIG. 1C shows the module of FIG. 1B in top view (epoxy foil side). The position of the electrodes on the underside of the module is shown in the narrow dashed line. The electrodes are not labeled for reasons of clarity. Also shown is the position of the through-going holes 104 in the epoxy relative to the underside metal electrodes. As shown diagrammatically, the layout of the module comprises three distinct regions. The central region of the module is the sensor region 12. This region of the module is proximal to a fluidic conduit in the card when the module is assembled into the diagnostic card, as described later. The region proximal to the location of the lower heater block of the card reader when the card is in the card reader's card insertion orifice is the heater contact region 13. More details of the relationship of the heater blocks of the card reader to the module in the card are given later. The region on the periphery of the module where electrical contact is made by the card reader to the metal electrodes on the underside of the module is the contact region 14. Those skilled in the art will appreciate that the same standard module fabrication technology can be used to make modules with many different electrode numbers and geometries. They differ only in the tooling to provide different locations of the through-going holes 104 (see FIGS. 1A and 1B), and the mask art-work used to photolithographically define different spatial arrangements of the formed metal elements 103. The general arrangement of any module according to this invention will include a sensor region 12 approximately centrally located, a heater contact region 13 at least partially adjacent the sensor region, and an electrical contact region 14 toward the module's periphery.

[0040]FIG. 2A shows a top plan view and FIGS. 2B-E show cross-sectional schematic views of a preferred embodiment of a diagnostic card in accordance with the invention, including a sensor array on an electrode module, including the card's relationship to elements of the card reader's card insertion orifice when the card is in the card insertion orifice during the use of the card. FIG. 2B shows one cross-sectional schematic taken along the fluidic path AA′ of FIG. 2A, the fluidic path extending from a calibrator fluid chamber 220 along a fluidic channel 210, through the measurement cell 211 to a waste channel 241. FIGS. 2C-E show schematics along the fluidic path BA′ of FIG. 2A, being along a fluidic path from the sample entry port 251 through the measurement cell 211 to the waste channel 241.

[0041] Referring to FIGS. 2A and 2B, the diagnostic card in the preferred embodiment is formed from a credit-card sized (85 mm ×53 mm ×1 mm thick) molded plastic card body 200 with an electrode module 101 as generally described above with reference to FIGS. 1A-1C embedded in the lower surface of the card body. The electrode module comprises an epoxy foil element 102 with die-cut through-going passages, the epoxy element being laminated with a metal foil that has been formed into eight electrode elements. Two electrode elements 130A, 130B are shown in FIG. 2B which have a sensor end 132A and 132B respectively and a contact end 131A, 131B respectively as are shown in the side-view schematic diagram. Membranes 207 and 208 are shown on the top surface of the module and contacting underside metal elements at the sensor ends 132A and 132B through the passages in the epoxy. The card body 200 also contains molded features (grooves, trenches and holes) on both its upper (solid lines in the top view schematic) and lower (dotted lines in the top view schematic) surfaces which molded features, when sealed by other laminating elements, form fluidic channels and a sealed fluid reservoir. Laminations are made to the lower and upper surface of the housing by label elements 201 and 202 and by metal foil elements 223A and 223B. Elements 201, 202 on the lower and upper surfaces of the card are label elements die-cut from an adhesive coated polymer sheet. Elements 223A and 223B are a lamination of two elements which are die-cut from a sheet of metal foil coated with polyethylene for heat sealing.

[0042] There are two trenches side by side on the lower surface of the plastic body. When clad by laminating elements 223A and 223B they form a reservoir chamber 220 with a volume of about 150 microliters. There is an orifice 221A through the plastic body 200 through which a calibrator fluid 224 is injected from the upper surface of the body to fill the chamber 220 during card manufacture, with another orifice 222, also through the body 200, for venting of air during the filling process. The chamber walls are defined by a pair of opposite foil elements 223A and 223B made of a plastic coated meal foil. The chamber 220, after filling with fluid, is completely sealed when the orifices 221 and 222 are closed-off during the lamination of foil elements 223A and 223B as is described in more detail later with reference to FIGS. 4B-D.

[0043] There is a fluidic channel 210 connecting the calibrator fluid chamber 220 to the measurement cell 211 at the electrode module's sensor region, and then to a waste channel 241. The diagnostic card also includes a sample inlet port 251 which is in fluid communication with a second channel 250 connecting the sample inlet port 251 to the measurement cell 211. There is a chamber outlet valve 230 for fluidically connecting the calibrator fluid chamber 220 with the connecting channel 210 between the measurement cell 211 and the calibrator fluid chamber without pressurizing fluid contained within the chamber. This means the valve structure is operated/operable independent of any pressurization of fluid in the chamber. The valve is preferably a rupturing structure for rupturing the wall of the sealed chamber at the connection with the connecting conduit for fluidically connecting the chamber to the conduit. In this preferred embodiment, the chamber rupturing structure includes a bore 233 through the body 200 and a rupture element, in this case plug 234, located in the bore and within the chamber 220 between the two metal foil elements 223A and 223B. The plug is slightly smaller in diameter than the bore, rendering it capable of axial movement therein, in this case upwards. The plug 234 is positioned so that a region of the metal foil element 223A on the peripheral edge of the plug (295 of FIG. 2D) ruptures when the plug is pushed upwards. Any other structures useful for the controlled opening of the chamber 200 for connection with the channel 210 when the card is in the card reader can also be used to function as the valve 230, as long as they do not lead to a pressurization of the chamber 220 during opening of the chamber. The diagnostic card further includes a delivery structure for forcing fluid from the chamber 220 under pressure, when the chamber contains fluid, and into the connecting conduit 210. In the preferred embodiment, the delivery structure is a portion of the chamber walls which is sufficiently flexible to be deformed, preferably from the exterior of the card and while the card is inserted in the card reader. Of course, the delivery structure can also be any other structure usable for reliably forcing fluid from the chamber when the chamber is fluidically connected to the connecting conduit..

[0044] FIGS. 2C-E schematically show the card in the card orifice of a card reader (the card reader preferably including a circuit board with detectors, amplifiers and other circuit components, as described in co-pending U.S. patent Publn. No. 2003/0148530A1) and illustrate the spatial relationship between elements of the card and elements of the cardreader's orifice during use of the device. In use, the card is first inserted into a card reader's card insertion orifice (FIG. 2C). The orifice comprises a lower generally planar mating element 280 which is co-planar with and proximal to the card's lower surface, and an upper generally planar mating element 290 which is co-planar with and proximal to the card's upper surface.

[0045] The card reader's card insertion orifice has a guide (not shown) to locate the features on the card with their respective mating features on the card reader insertion orifice's planar mating elements during card insertion. After insertion, the two mating elements of the card reader insertion orifice are moved toward each other, thus clamping the card between them. The construction and function of the card reader is described in detail in co-pending U.S. patent Publn. No. 2003/148530A1, incorporated herein by reference. As the lower surface of the card is brought into contact with the lower mating element 280 of the card reader's card orifice, a pin element 282 provided on the mating element 280 first contacts the card at the calibrator fluid chamber outlet valve 230. The pin 282 pushes plug 234 upwards. This lifts the metal foil laminate above the plug causing foil 223A to break at location 295 (FIG. 2D), thus fluidically opening the calibrator fluid chamber. At the same time, the electrode module is electrically contacted by a contacting means of the card reader which comprises a contacting array of eight metal contact elements formed in a metal film or foil 286 on an insulating flex connector substrate 287. Two of the eight pins are shown in the side view schematics of FIG. 2C-E. Each has a contact end 283A, 283B for making z-action contact to the module's electrode contact locations 131A, 131B on the lower surface of the electrode module, and an end 284A, 284B for connection to an electrical circuit elsewhere in the card reader. The flex connector at its module contacting end is mounted on the movable end of a set of flexible cantilevers 285A and 285B, preferably made of plastic, whose other end is embedded in the lower mating element 280 of the card reader orifice The cantilevers, with the flex connector mounted on it, are in their at-rest position raised above the plane of the lower mating element 280 at the location of contact to the module, so that as the card is clamped to the lower mating element of the card reader orifice the cantilevers are depressed, thus providing z-action contact force to the electrical contacts made between the flex connector of the card reader and the electrode module of the card. At the same time the card's electrode module is thermally contacted by a lower heater block 289 and the top of the diagnostic card above the measurement chamber by an upper heater block 291. The lower heater block 289, which is mounted in the card reader orifice's lower mating element 280, makes thermal contact with the module on its lower surface directly under the measurement chamber 211, making physical contact to the module's ‘split ring’ heater contact metal elements 134A, 134B, while being in close proximity to the other metal elements elsewhere on the module, but electrically isolated from them. At the same time, the upper heater block 291, which is mounted in the card reader orifice's upper mating element, makes thermal contact to the card directly above the measurement chamber 211. Each heater block contains a heater element and a temperature measuring element each in intimate thermal contact with the block (not shown). The blocks' heater elements and temperature measuring elements are also connected to the card reader's electrical circuit. The lower mating element 280 of the card reader also includes an actuator element 281 positioned to be opposite the calibrator fluid chamber 220 when the card is inserted into the card reader's card orifice. As the card continues to be clamped between the mating surfaces, the actuator element 281 now engages the delivery structure of the calibrator fluid chamber 220, deforming the chamber wall 223 and compressing the chamber 220, thereby pressurizing the chamber contents and causing delivery of fluid out of the chamber along fluidic channel 210 to measurement chamber 211 (FIG. 2E). When the card is fully clamped in the card reader orifice (FIG. 2E) there is a period of time during which the module, the sensors and the fluid in the measurement cell are heated, preferably to 37.4° C., followed by a period of time during which the module's sensors are calibrated. After this calibration period, the card-reader prompts the user to supply sample fluid to the diagnostic card. The user engages a syringe containing sample fluid to the card's sample entry port (251 of FIGS. 2A and 2B). The syringe tip forms a seal with an adhesive element 253 surrounding the entry port. The sample port 251 may optionally be reversibly sealed with a closure flap which can be part of the label 202. The user delivers sample fluid from the syringe to the measurement cell 211 along channel 250, thus displacing calibrator fluid out of chamber 211 to waste channel 241. The module's sensors now generate sensor signals derived from the sample fluid, which electrical signals are extracted from the electrode module via the card reader's electrical flex connector 287 to an electrical circuit in the reader. After completion of the measurement cycle, the card is unclamped and withdrawn from the card reader's orifice.

[0046] Referring again to FIG. 2, the card is assembled as follows in three principle steps. Step 1: sealing the electrode module 100 to plastic card body 200. Step 2: forming the metal foil cladding around chamber 220 by laminating first lamination 223A and second 223B lamination of metal foil elements with insertion of the rupture plug 234 between these laminations; filling of the clad calibrator chamber 220 with calibrator fluid 224; then sealing calibrator fluid and plug into the clad chamber. Step 3: laminate top 202 and bottom 201 labels. Steps 1 and 2 will now be described in more detail.

[0047]FIG. 3A and B show in more detail the electrode module assembled into the plastic card body 200 in step 1 of the assembly process. Referring to FIG. 3A, the molded plastic card body 200, as received from the vendor, is first laminated with the electrode module 100 whose epoxy foil upper surface 102 faces the card body and is recessed into it and sealed with adhesive 303. The adhesive is applied to the outer area of the module's epoxy surface perimetric to the module's central sensor region. As shown in FIGS. 3A and 3B the adhesive is applied to the entire top epoxy surface, except the sensor region (region 12 shown in FIG. 1C). The module, when embedded in the card, is coplanar with the card body with the module's upper sensor surface proximal to the card body's fluid measurement cell 211 and the module's lower metal surface 103 facing the outside.

[0048]FIGS. 3A and 3B also show in more detail the location of the card reader's heater blocks relative to the card and its electrode module when the card is clamped in the card reader's card insertion orifice. FIG. 3A shows a cross-section along AA′ of the electrode module shown in FIG. 1C, which is in the direction orthogonal to the card's fluidic channel over the electrode module. FIG. 3B shows a cross-section along BB′ of the electrode module shown in FIG. 1C, which is in the direction along the path of the card's fluidic channel over the electrode module. As shown in FIG. 3A, the lower heater block 289 physically contacts the electrode module at the locations 134A and 134B which are the electrode module's heater contact metal elements. The lower heater block 289 is in close proximity to (thus thermally connected with) but electrically isolated from, other metal elements of the electrode module 100, including the sensor ends 132 and contact ends 131 of the electrodes and the metal paths 133 between them. The lower heater block 289 extends a distance beyond the width of the fluidic measurement chamber 211. As shown in FIG. 3B the lower heater block is in close proximity to the metal paths 133 connecting the electrodes' sensor ends 132 to their contact ends 131 but not in physical contact with them. The upper heater block 291 makes contact to the card's upper plastic label. It too extends beyond the width of the measurement chamber 211 (FIG. 3A), but also extends a distance along the fluidic channel beyond the electrode module on both sides (FIG. 3B). We have found that when the upper heater extends about 5 mm beyond the module there is satisfactory thermal bootstrapping of the fluid beyond the sensor region of the module, thus assuring excellent thermal control of the temperature of the sensor region.

[0049] We have found that when the card is fully clamped in the card reader's orifice, at which time the lower heater block 289 contacts the electrode module's heater contacts 134, the regions of the heater block not in contact with, but in proximity to the module, should be spaced about 25 micrometers from the module's metal surface: At this distance there is still satisfactory heat transfer from heater block to module, but there is also reliable electrical isolation during repeated use of the card reader. In general, the rate of heat transfer from the heater block to the module increases with decreasing spacing. The preferred range of spacing is 10 to 50 micrometers. However, the person skilled in the art will appreciate that a spacing below 10 micrometers may be usable as long as reliable electrical insulation of the heater block from the sensing and contacting regions of the module is ensured. A spacing above 50 micrometers is usable, but the heat transfer rate will be low.

[0050]FIG. 4 shows in more detail the metal foil clad calibrator fluid chamber 220 and the foil rupturing plug, and its forming, filling and sealing processes which together are step 2 of the card assembly procedure. Referring to FIG. 4A which is a top view schematic of the card's calibrator fluid reservoir region and FIG. 4B which is a cross-section through the embodiment of FIG. 4A taken along line M′, being along the fluidic path from the calibrator fluid fill hole 221 along the calibrator fluid reservoir 220, its connecting channel 405 to the vent hole 222. The card body 200 in the calibrator fluid reservoir region of the card features a molded calibrator fluid reservoir cavity 401 (shown here as two parallel cavities fluidically connected), a molded trench 405 connecting the cavity 401 to a rupture-plug bore 233 and a second trench 210 connecting the rupture-plug bore to the measurement cell 211 (see FIG. 2A). A first metal foil element 223A has a pressure sensitive adhesive on one side of the metal and approximately 25 micrometers thickness polyethylene coating on the other. The element 223A, which is die cut from a sheet and placed with its adhesive side down onto the card body, extends over the calibrator fluid reservoir cavity 401, the connecting channel 405 and the rupture-plug bore 233, overlaying all these features and extending to a perimeter beyond them. When high air pressure is applied to the foil element 223A it deforms taking the contour of the card body's reservoir cavity 401, connecting channel 405 and rupture-plug hole 233, being then attached to the body's surface by the pressure sensitive adhesive. The polyethylene coated surface of foil element 223A faces the inside of the reservoir cavity. The foil deforming procedure is similar to the blow-molding process well known in the art. In manufacture, a tool with an air pressurizable cavity is engaged to the foil on the card body and sealed to it about the cavity, preferably by an elastomeric gasket. When high pressure air is introduced into the tool's cavity, the air blow-deforms the metal foil to take the contour of the card body. It will be readily apparent to the person skilled in the art that other methods of shaping the foil element 223A to take on the contour of the card body may also be used, such as hydroforming. A rupture-plug element 234, which is a rigid disc approximately the same thickness as the card body with a diameter somewhat smaller than the diameter of the rupture-plug bore 233, is placed onto the foil element 223A in the depression in the foil formed over the rupture-plug bore 233. The foil element 223A is pierced at the bottom of fluid fill hole 221 and vent hole 222. A second polyethylene coated metal foil element 223B is laminated over the first foil element 223A with its polyethylene coating facing the polyethylene coating of element 223A. A heat seal is made between foil elements 223A and 223B, by fusing the two polyethylene coating layers, everywhere except in the fill and vent regions 415 and 416 adjacent the fluid fill and vent holes 221 and 222 respectively. At this stage, the foil clad calibrator fluid reservoir is sealed except for the fill and vent holes 221, 222 as shown in FIG. 4B and is now ready to receive fluid. Calibrator fluid 224 is introduced through fill hole 221 into chamber 220 filling it and partially filling the channel 405 while expelling air from the chamber through vent hole 222. In the final step, once the chamber 220 is filled, the fill and vent regions 415 and 416 near the fill and vent holes 221, 222 are then sealed in a secondary heat seal process, thus entirely sealing the calibrator fluid and rupture plug within the two foil elements as shown in FIGS. 4C and 4D. Lamination of the card body 200 with an upper pressure sensitive adhesive coated label element 202 now forms a channel 210 which fluidically connects the region 450 of the calibrator chamber where the rupture of the foil takes place (FIG. 4D) with the measurement cell 211 (see FIG. 2A). A second lower label lamination 201 which leaves the lower surface of the electrode module 100 exposed completes the card assembly.

[0051] Using the above recited fluid chamber design and manufacturing procedure we have achieved a remarkably long period of calibrator fluid storage stability. The mean time to failure of a sealed fluid used for sensor calibration is the time for the carbon dioxide partial pressure to drop from its initial value in the fluid to an unacceptably low level as the gas permeates out through the heat fused polyethylene seam. We have found that we can achieve greater than 6 months room temperature storage stability in which time the partial pressure of carbon dioxide changes from it's average value by less than 0.5 mm Hg. To achieve this we have designed the perimeter seal width to be greater than 3 mm width at all locations along the perimeter. This high level of stability is in marked contrast to other devices of the known art, which must be stored in the refrigerator to achieve extended lifetime. Using the above recited fluid chamber design with incorporated rupture plug we have achieved a simple foil rupturing method which opens the foil-sealed chamber during the use of the device, but before the calibrator fluid in the chamber is pressurized to expel it from the chamber and to the measurement cell. This achieves a high level of reliability and control in the calibrator fluid delivery step of the device's operation.

[0052] Those skilled in the art will recognize that the various inventive elements of the diagnostic card can be used together as they are in the card of this disclosure, or they can be used separately in different card designs. For example, the sealed fluid chamber and its valve structure means can be incorporated into diagnostic cards comprising micro-porous fluidic elements such as those as disclosed in U.S. patent application Ser. No. 10/649,683. In this case the sealed fluid is used for priming the micro-porous pump elements rather than for sensor calibration purposes. The inventive fluidic arrangements and sealed fluid chamber can be advantageously used with electrode modules comprising foil laminates as described in this disclosure, but they can also be used with sensor modules of other kinds, including the many types of sensor modules of the known art which are fabricated on a planar insulating substrates (microfabricated chips, planar circuit boards and the like) and including sensor modules incorporating non-electrochemical sensing means such as optical, chemiluminescence or fluorescence, as are known in the art. Indeed, these inventive fluidic components will be useful in any unit-use diagnostic card incorporating an on-board fluid. 

1. A diagnostic card for use with a card reader in sensing at least one component concentration of a fluid sample, comprising: a card body at least one component sensor located in a sensor region of the card body; a sealed chamber defined in the card body outside the sensor region for containing a fluid; a fluid conduit for fluidically connecting the chamber with the sensor region; a valve located in the chamber for fluidically connecting the chamber to the fluid conduit; and a delivery structure separate and distinct from the valve for forcing fluid from the chamber, when the chamber contains fluid, and into the fluid conduit.
 2. The diagnostic card of claim 1, wherein the chamber is formed of a laminate of two opposed, plastic coated metal foil laminations bonded about their perimeter by a first heat seal made by melt bonding the plastic coatings of the laminations.
 3. The diagnostic card of claim 2, wherein the heat seal has a width of at least 3 mm.
 4. The diagnostic card of claim 1, wherein the chamber includes separate fill and vent openings for filling of the chamber with a fluid without pressurization.
 5. The diagnostic card of claim 4, wherein the chamber is filled with fluid and the fill and vent openings are sealed to completely seal off the filled chamber.
 6. The diagnostic card of claim 5, wherein the chamber is formed of a laminate of two opposed, plastic coated metal foil laminations bonded about their perimeter by a first heat seal made by melt bonding the plastic coatings of the laminations and the fill and vent openings are sealed by a second heat seal made by melt bonding the plastic coatings of the laminations about the fill and vent openings.
 7. The card of claim 1, wherein the chamber is sealed by a chamber wall, the card body includes a valve seat and the valve includes a valve body displaceably received in the valve seat, the valve body and valve seat being shaped and constructed for rupturing a portion of the chamber wall upon displacement of the valve body relative to the valve seat.
 8. The card of claim 2, wherein the valve includes a valve body displaceably received in a valve seat in the card body, the valve body being sandwiched between the laminations within the chamber, the valve body and valve seat being shaped and constructed for rupturing one of the laminations upon displacement of the valve body relative to the valve seat.
 9. The card of claim 8, wherein the valve body is a rupture plug and the valve seat is a plug receiving bore in the card body.
 10. The card of claim 9, wherein the plug and plug receiving bore include cooperating edges for rupturing the one of the laminations upon displacement of the plug in the plug receiving bore.
 11. The card of claim 2, wherein the card body includes molded contours and one of the foil laminations is pressure-formed into the contours of the card body.
 12. The card of claim 1, wherein the chamber has a chamber wall and a chamber volume and the delivery structure is formed by a flexible portion of the chamber wall which is deformable for reduction of the chamber volume.
 13. The card of claim 1, wherein the chamber is made of a pair of opposed, plastic coated metal foil laminations defining the chamber wall and bonded about their perimeter by a first heat seal achieved by melt bonding the plastic coatings of the laminations about their perimeter, the card body further including a fill opening in communication with the chamber through one of the laminations for filling of the chamber with a fluid; and a vent opening remote from the fill opening and in communication with the chamber through one of the laminations for venting of air in the chamber during filling of the chamber with the fluid, the fill and vent openings being sealable for complete sealing of the chamber by a second heat seal melt bonding the plastic coatings about the fill and vent openings.
 14. An electrode module for use in a diagnostic card for sensing at least one component concentration in a fluid sample, comprising a substantially planar insulator layer; and a substantially planar metal conductor layer laminated to the insulator layer; the electrode module having a centrally located sensing region, a peripherally located contacting region and an intermediate heating region, the insulator layer in the sensing region having a number of throughgoing apertures, a sensor membrane in each aperture for contact with the sample and for electrical contact with the conductor layer, the conductor layer being divided into a corresponding number of conductor elements and a heater contact element, each conductor element including a conductor path having a sensor end and an opposite contact pad end, the sensor ends being located in the sensing region of the module and below one of the apertures respectively and the contact pad ends being located in the contact region, the heater contact element being electrically insulated from the conductor elements and surrounding the sensing region in the heating region, the heater contact element having a connecting gap extending between the sensing and contact regions and the conductor paths extending through the connecting gap.
 15. The electrode module as defined in claim 14, wherein the insulator layer is an epoxy resin foil and the conductor layer is a metal foil.
 16. An electrode module as defined in claim 14, wherein the conductor paths are tortuously long to reduce thermal conduction along the conductor paths.
 17. The electrode module as defined in claim 14, wherein the heater contact element includes a pair of connecting gaps located on opposite sides of the heating region and the conductor paths each extend through one of the connecting gaps.
 18. The electrode module as defined in claim 14, wherein the heater contact element includes multiple connecting gaps corresponding in number to the conductor elements, each conductor path extending through one connecting gap.
 19. The electrode module as defined in claim 18, wherein the connecting gaps and contact pad ends are positioned about the sensing region in such a way that all conductor paths are of equal length.
 20. The electrode module as defined in claim 15, wherein the module has a rectangular shape and the contacting region extends along a pair of opposite sides of the electrode module, the module including eight apertures and eight conductor elements, the contact pad ends being symmetrically evenly distributed in the contacting region in two rows along the opposite sides and the sensor ends being symmetrically arranged in two parallel rows in the sensing region.
 21. A diagnostic card for use with a card reader for sensing at least one component concentration of a fluid sample, comprising a card body having a measurement cell for containing a sample fluid; a passage for supplying the sample fluid to the measurement cell; and an electrode module mounted to the card body and including a substantially planar insulator layer and a substantially planar metal conductor layer laminated to the insulator layer; the electrode module having a centrally located sensing region, a peripherally located contacting region and an intermediate heating region, the insulator layer in the sensing region having a number of throughgoing apertures, a sensor membrane in each aperture for contact with the sample fluid and for electrical contact with the conductor layer, the conductor layer being divided into a corresponding number of conductor elements and a heater contact element, each conductor element including a conductor path having a sensor end and an opposite contact pad end, the sensor ends being located in the sensing region of the module and below one of the apertures respectively and the contact pad ends being located in the contact region, the heater element being located in the heating region and electrically insulated from the conductor elements and surrounding the sensor region, the heater element having a connecting gap extending between the sensor and contact regions and the conductor paths extending through the connecting gap; the electrode module being mounted to the card body for exposure of the sensor membranes to the measurement cell and for external access to the contact pad ends and the heater contact element.
 22. The diagnostic card as defined in claim 21, wherein the insulator layer is an epoxy resin foil and the conductor layer is a metal foil.
 23. The diagnostic card as defined in claim 21, wherein the insulator layer is adhesively bonded to the card body about the sensing region for preventing leakage of any fluid contained in the measurement cell about an edge of the electrode module to the conductor layer.
 24. The diagnostic card as defined in claim 21, wherein the conductor paths are tortuously long to reduce thermal conduction along the conductor paths.
 25. The diagnostic card as defined in claim- 21, wherein the heater element includes a pair of connecting gaps located on opposite sides of the heating region and the conductor paths respectively extend through one of the connecting gaps.
 26. The diagnostic card as defined in claim 21, wherein the module has a rectangular shape and the contacting region extends along a pair of opposite sides of the electrode module, the module including eight apertures and eight conductor elements, the contact pad ends being symmetrically evenly distributed in the contacting region along the opposite sides of the electrode module and the sensor ends being symmetrically arranged in two parallel rows in the sensing region.
 27. The diagnostic card of claim 21, further including a passage for draining excess fluid away from the measurement cell.
 28. A diagnostic card reader for use with a diagnostic card having substantially planar opposite first and second surfaces, a measuring region and an electrode module located in the measuring region and having a conductor layer exposed in the first surface, the conductor layer being divided into a substantially central sensing region, a substantially peripheral contacting region including electrode contact ends, and an intermediate heating region surrounding the sensing region and including a heater contact element, the card reader comprising: a housing; a card cavity for receiving at least a portion of the diagnostic card to locate the conductor layer of the electrode module inside the card cavity; a contacting arrangement for electrically contacting at least one of the electrode contact ends of the electrode module when the card is received in the card cavity; and a first heater block for heating the sensing region of the electrode module when the card is received in the card cavity, the heater block having a first block portion for physically contacting the heater contact element of the electrode module and heating the heating region by direct thermal conduction, and a second block portion backset from the first portion to be spaced apart parallel to the sensing region of the electrode module when the first block portion is in physical contact with the heater contact element for heating the sensing region by indirect thermal transfer.
 29. The card reader of claim 28, wherein the contacting arrangement includes at least one metal contacting element in the form of a formed metal film carried on a flex substrate mounted on a flexible support in the card reader's card insertion orifice for resiliently contacting the contact end when the card is received in the card cavity.
 30. The card reader as defined in claim 28, further comprising a second heater block for physically contacting the second surface of the card in the measuring region for heating at least the portion of the measuring region which coincides with the sensing region of the card and for heating any liquid within the card in the measuring region.
 31. The card reader as defined in claim 30, wherein the heater block extends beyond the measuring region for heating fluid in any conduits in the card leading to and from the measuring region.
 32. A diagnostic card for use with a card reader for sensing at least one component concentration of a fluid sample, comprising: a planar card body having a pair of opposite planar surfaces; at least one sensor located in a sensor region of the card body; a sample entry port on one of the surfaces of the card; a sample conduit within the card body for fluidically connecting the sample entry port to the sensor region; and an adhesive gasket surrounding the sample entry port for forming a liquid seal about a conduits inserted into the sample entry port for sample fluid injection.
 33. A method of forming a sealed fluid reservoir in a diagnostic card, comprising the steps of obtaining a diagnostic card body with a reservoir recess in a surface of the card body; lining the recess with a first laminate of a plastic film layer and an aluminum foil layer, the foil layer contacting the card body and the first laminate extending beyond the recess; placing a second laminate of a plastic film layer and an aluminum foil layer over the first laminate so that the plastic film layers contact one another; and forming a sealed reservoir by heat bonding the film layers along a periphery of the first and second laminates forming a continuous heat bond line.
 34. The method of claim 33, wherein the first laminate is pressure formed into the recess to closely follow a contour of the recess.
 35. The method of claim 33, wherein the heat bond line has a minimum transverse width of 3 mm.
 36. The method of claim 33, wherein the recess includes a filler passage and a vent passage and the method includes the additional steps of perforating the first laminate over the filler and vent passages to form filler and vent openings therein, filling the sealed reservoir after heat bonding of the film layers by injecting fluid through the filler opening, and sealing the reservoir by forming a second heat bond of the film layers about the filler and vent openings.
 37. The method of claim 34, comprising the further step of, prior to placement of the second laminate, placing a rupture plug on the first laminate at a desired location of rupture so that the rupture plug is contained in the reservoir after heat bonding of the film layers.
 38. The method of claim 37, wherein the card body includes a plug receiving bore, the first laminate is pressure formed into the recess to closely follow a contour of the recess and the plug receiving bore, the plug is shaped and sized to slidably fit into the plug receiving bore, and the plug is placed at the location of the plug receiving bore prior to placement of the second laminate. 